If you have luggage, the easiest by far is taking an Uber/cab. It is the fastest and more direct way to get to the terminal without needing to navigate the subway system.
You have a few choices. From Penn Station, you can hop on a # 1, 2, or 3 train one stop uptown to 42nd Street and hop on the shuttle bus to the pier, or you can just grab a cab, not far at all.
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